This was followed by more rain in early 1973, with river flow cresting on March 31 at Red River Landing, Louisiana, and a heavy snowmelt in the Rocky Mountains which caused western tributaries such as the Missouri and Arkansas to form a final catastrophic high in June.

The largest single inundation, south of St. Louis, Missouri, was caused by a series of catastrophic levee failures on the west bank of the river and ultimately covered almost 9,400 square miles (24,000 km2).

[4] The Morganza Spillway was opened, flooding portions of the Atchafalaya River basin in Louisiana and causing the deaths of thousands of head of livestock and white-tailed deer.

[1] Red River Landing, Louisiana reached 58.22 feet on May 13 and was 9th highest crest of record.

Farther down the River at Donaldsonville the flood stage reached 32.30 feet on April 9, which was the 10th highest crest of record.